Early Regeneron tests suggest antibody drug may be less effective against Omicron

Initial testing indicates that mutations in the Omicron variant of the coronavirus could interfere with the antibody drug Regeneron’s ability to treat Covid-19.

This finding is the first sign that treatments developed to deal with Covid-19 may have lost their effectiveness as the virus evolved. “The individual mutations present in the Omicron variant indicate that it is possible to reduce the neutralizing activity of both vaccine- and monoclonal antibody-mediated immunity,” Regeneron said Tuesday.

Tests to date have been performed using laboratory and modeling samples. “Further analyzes are underway to confirm and quantify this potential impact using actual Omicron variant sequences,” it added.

Regeneron’s share price fell more than 2.8% in pre-market trading. Global markets fell on Tuesday after Moderna chief executive Stéphane Bancel told the Financial Times he thinks existing vaccines will struggle to fight the Omicron variant.

Regeneron’s Regen-Cov treatment is made up of a mixture of two monoclonal antibodies that block the virus that causes Covid-19 and is widely used to treat patients.

Regeneron says it has a large collection of monoclonal antibodies, and early analyzes suggest that some of the next-generation antibodies it is developing may remain effective against Omicron.

Eli Lilly, another maker of antibody drugs to treat Covid-19, did not immediately respond to a request for comment.